The long term goal of this project continues to be the understanding of the process of amino acid transport from mother to fetus. This goal is approached by investigation on a cellular and subcellur level of the mechanism and regulation of transport and the biochemical processes that may be expected to underlie it. Investigations will continue to use both in vitro incubation of human placental villous tissue and isolated plasma membranes from the syncytiotrophoblast. We have demonstrated that the isolated membranes are suitable for study of glucose as well as amino acid transport. Glucose is a major fetal nutrient and broadening the studies to include its transport will lead to a more integrated knowledge of the structure and function of the synctial plasma membranes. Therefore, these studies will be pursued in association with those of amino acid transport. As far as possible, our investigation of transport will use quantitative or semi-quantitative techniques to attept to elucidate mechanisms of placental transfer and their controls. With the aim of relating the results to the metabolic needs of the fetus and placenta and to knowledge of the overall process of placental transfer. The methods of approach include the characterization of isolated membrane preparations and their incubation in vitro to measure uptake and define transport systems. Using incubated villous tissue and membranes we will study effects of hormones and nother potential regulatory substances and elucidate mechanisms which may regulate transport in the syncytium. Finally, we will investigate various physical and molecular characteristics of microvillous membrane transport proteins.